In communication between terminals, between a server and a terminal, or the like, communication speed is affected by the state of a terminal, the state of a server, a bandwidth shortage of a network, and the states of the devices through which communication is made. Throughput is used as an indicator indicating a communication speed.
FIG. 18 is a diagram for explaining throughput. As illustrated in FIG. 18, there are two kinds of throughput, that is to say, effective throughput and maximum effective throughput. The effective throughput is a processing capacity (the amount of data transfer) per unit time, which was actually able to be used. On the other hand, the maximum effective throughput is throughput of when a free bandwidth excluding traffic of the other terminals has been used up in a bottleneck section.
In FIG. 18, if it is assumed that the throughput of when the transmission path is fully occupied is 100 Mbps (100 megabits per second), and the other terminals are using a bandwidth for 50 Mbps, the maximum effective throughput is 50 Mbps. On the other hand, the measurable effective throughput is less than the maximum effective throughput and is 30 Mbps, for example. Whether or not the free bandwidth of a network is fully used is determined by the maximum effective throughput.
In this regard, a related-art technique for achieving data transmission based on a reliable and efficient rate setting is provided. In this technique, rate control is performed with maximum throughput calculated based on a data transmission-and-reception period excluding a data transmission-and-reception non-execution period having no contribution to data transmission and reception as the upper limit.
Also, a related-art technique for using radio resources efficiently and improving system throughput is provided. In the technique, a NACK is discarded if a time interval obtained based on a NACK reception time and a transmission time of data re-transmitted immediately before the NACK reception is less than the round trip time (RTT).
As a related-art example, Japanese Laid-open Patent Publication Nos. 2006-279283 and 2013-34048 are known.
Whether or not a delay in communication is caused by a bandwidth shortage of a network is determined by the fact of whether or not a free bandwidth of the network is fully used. However, throughput that is able to be measured currently is effective throughput. The bandwidth used by the other terminals is not fixed, and thus there is a problem in that it is difficult to measure the maximum effective throughput used for determining whether or not the free bandwidth of the network is fully used.